Heat exchangers such as automobile radiators and similar types employing tube bundles with header-tanks at each end and provisions for flowing one fluid through the interior of the exchangers and another fluid such as air over the outer surfaces have long been made of copper, aluminum, brass and other such relatively lightweight and weak metals and alloys. In such exchangers the joints between the parts have customarily been soldered or brazed. As a result of the soft metal and this type of joint it has been necessary to provide supporting structure for the weak exchangers such as a supporting framework in which an automobile radiator, for example, is mounted.